1. Field of the Invention
The present invention relates to a radio clock and, in particular, to a clock which employs a photoelectric element to determine whether the hour pinion, the minute pinion, and the second pinion reach their position points, and to be able to quickly complete the positioning of the hour hand, the minute hand, and the second hand.
2. Description of the Prior Art
Radio clocks can receive the timing information sent from an emitting station, and the information can be used as a reference time on time setting. Referring to FIG. 1, a radio clock typically comprises an antenna 11, a receiving circuit 12, and a processor 13. The receiving circuit 12 receives the timing information sent from an emitting station by the antenna 11, and then the receiving circuit 12 transmits the information to the processor 13, which controls and handles the process of time setting. In general, when the time-setting function of a radio clock is actuated, the hour hand, the minute hand, and the second hand will be controlled and moved to the position points which typically is the zero (twelve) o""clock, zero minute, and zero second. The hour hand, the minute hand, and the second hand will then be adjusted to the position corresponding to the received timing information. A positioning mechanism is needed for moving the hour hand, the minute hand, and the second hand to the position points in a controlled manner. For a mechanic radio clock whose hour pinion, minute pinion, and second pinion are driven by motors, the positioning mechanism employs photoelectric elements to determine whether the hour pinion, the minute pinion, and the second pinion reach the position points. Referring to FIG. 1 again, the radio clock employs two motors 14, 15 to drive the second pinion and the minute pinion respectively, and employs then the minute pinion to drive the hour pinion. In this way, the hour hand, the minute hand, and the second hand can be moved in a controlled manner. Two photoelectric elements are also employed to carry out the positioning of the hour hand, the minute hand, and the second hand by detecting the identifying position points on the hour pinion and the second pinion as shown in FIG. 2. In FIG. 2, only the hour hand and the minute hand are shown, the photoelectric element 16 is employed to detect the position point 17 of the hour pinion 18. When the photoelectric element 16 detects the position point 17, the hour hand and the minute hand corresponding to the hour pinion 18 and the minute pinion 19 should be located at the zero (twelve) o""clock and zero minute. The positioning of the second hand also employs the same technique, i.e. a photoelectric element is employed to detect the identifying position point on the second pinion. In this way, the photoelectric elements can determine whether the hour hand, the minute hand, and the second hand are located at the position points. It is now considered that, when the radio clock actuates the time-setting function at one o""clock and zero minute, the second pinion can reach its position point of zero o""clock after rotating at most one round (assume the second pinion to be at zero o""clock just before the time setting starts) and the minute pinion shall rotate eleven rounds before driving the hour pinion to the position point of zero o""clock. Obviously, it is time consuming for a traditional radio clock to carry out the positioning of the hour hand, the minute hand, and the second hand. If a positioning mechanism can be developed to quickly drive the hour hand, the minute hand, and the second hand to the position points by employing only one photoelectric element, the cost can be cut down and the reduction in time bears positive meaning.
The object of the present invention is to provide a radio clock which can quickly complete the positioning of the hour hand, the minute hand, and the second hand.
The other object of the present invention is to provide a positioning mechanism which employs only one photoelectric element in determining whether the hour hand, the minute hand, and the second hand reach the position points, when the time-setting function of the radio clock is actuated.
For more detailed information regarding this invention together with further advantages or features thereof, at least an example of preferred embodiment will be elucidated below with reference to the annexed drawings.